HI7191IPZ - 24-Bit Sigma-Delta ADC, ±5V, 20-PDIP | Renesas
MPN: HI7191IPZ ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $18.5 | $18.50 |
| 10 | $16.2 | $162.00 |
| 100 | $13.95 | $1,395.00 |
| 500 | $12.1 | $6,050.00 |
| 1,000 | $10.5 | $10,500.00 |
HI7191IPZ Overview
An ADC of the sigma-delta type is a noise-shaping converter that oversamples the input at a rate far above the Nyquist frequency and pushes quantization noise out of the baseband, trading speed for resolution. The HI7191IPZ is part of the instrumentation ADC category, which sits hierarchically inside precision data converters, alongside successive-approximation (SAR) ADCs at lower resolution and wider bandwidth. Compared with successive-approximation ADCs, instrumentation sigma-delta converters such as the HI7191IPZ deliver far higher effective resolution at low word rates while integrating input conditioning, making them ideal for direct connection to bridge sensors, thermocouples, and other low-level differential sources.
Key differentiating features include 24-bit resolution, the on-chip PGIA with gains of 1, 2, 4, 8, 16, 32, 64, and 128, on-chip calibration registers that allow user-initiated self- and system-calibration routines, and a low-power standby mode controlled through the serial interface. The combination of differential inputs, a differential reference, and integrated gain front-end allows the converter to maintain high common-mode rejection and resolution over the full-scale input range.
The converter architecture combines a charge-balancing modulator, a digital decimation filter, and the integrated PGIA, yielding a single-chip instrumentation front-end. The HI7191IPZ targets a maximum output word rate of approximately 2 kSPS at full 24-bit resolution, making it suited to DC and quasi-DC precision measurements rather than wideband signal acquisition. The HI7191IPZ is pin-compatible with the HI7190IPZ, which shares the same die but offers tighter linearity specifications for the most demanding calibration channels.
Typical applications include precision weighing scales and load-cell readouts, industrial process-control pressure and strain instrumentation, laboratory and analytical instrumentation such as pH and conductivity meters, thermocouple and RTD temperature acquisition modules, and battery-powered portable instrumentation where the standby mode and low input current draw help extend operating life. Designers most often place the HI7191IPZ between the transducer bridge and an external microcontroller, with the MCU configuring PGIA gain, calibration, and channel selection via the four-wire synchronous serial interface.
Key design considerations include providing well-decoupled analog and digital ±5V supplies, buffering inputs where source impedance is high, and writing a calibration routine that exercises the on-chip zero-scale and full-scale registers. Note that the HI7191IPZ is currently listed as obsolete on the Renesas product page, so designers should confirm long-term availability or plan around the pin-compatible HI7190IPZ.
This page synthesizes distributor pricing, package information, parametric comparison data, and pin-compatible alternatives not aggregated on any single distributor page.
Drop-in alternatives for HI7191IPZ — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
HI7190IPZ
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HI7191IP
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HI7191IPZ Maximum Ratings & Electrical Characteristics
| Resolution | 24 bit |
| Architecture | Sigma-Delta |
| Number of Channels | 1 |
| Conversion Rate (max) | 2 kSPS |
| Analog Supply Voltage | +/-5 V |
| Digital Supply Voltage | +/-5 V |
| Input Type | Differential |
| Reference Input | Differential |
| On-chip PGIA Gain Range | 1 to 128 (1, 2, 4, 8, 16, 32, 64, 128) |
| Serial Interface | SPI / SSR synchronous serial |
| On-chip Calibration | Yes (self and system cal) |
| Standby Mode | Yes (via serial command) |
| Package | 20-PDIP |
| Mounting Type | Through-Hole |
HI7191IPZ Pin Configuration
| Pin 1 | V+ — Analog positive supply |
| Pin 2 | AIN+ — Differential analog input positive |
| Pin 3 | AIN- — Differential analog input negative |
| Pin 4 | REF+ — Differential reference input positive |
| Pin 5 | REF- — Differential reference input negative |
| Pin 6 | AGND — Analog ground |
| Pin 7 | V- — Analog negative supply |
| Pin 8 | CLK — External clock input |
| Pin 9 | DGND — Digital ground |
| Pin 10 | SDAT — Serial data output |
| Pin 11 | SCLK — Serial clock input |
| Pin 12 | CS — Chip select (active low) |
| Pin 13 | RESET — Reset / standby control |
| Pin 14 | [DATA_NEEDED: pin 14] — [DATA_NEEDED: pin function not in verified web data] |
| Pin 15 | [DATA_NEEDED: pin 15] — [DATA_NEEDED: pin function not in verified web data] |
| Pin 16 | [DATA_NEEDED: pin 16] — [DATA_NEEDED: pin function not in verified web data] |
| Pin 17 | [DATA_NEEDED: pin 17] — [DATA_NEEDED: pin function not in verified web data] |
| Pin 18 | [DATA_NEEDED: pin 18] — [DATA_NEEDED: pin function not in verified web data] |
| Pin 19 | [DATA_NEEDED: pin 19] — [DATA_NEEDED: pin function not in verified web data] |
| Pin 20 | [DATA_NEEDED: pin 20] — [DATA_NEEDED: pin function not in verified web data] |
Typical Applications
HI7191IPZ is suitable for 6 applications: Precision Weighing Scales and Load Cells, Industrial Pressure and Strain Instrumentation, Laboratory pH and Conductivity Meters, Thermocouple and RTD Temperature Acquisition, Portable Battery-Powered Instrumentation, Process Control Analog Input Modules.
Precision Weighing Scales and Load Cells
The HI7191IPZ is well suited to weigh-scale and load-cell readouts because its 24-bit sigma-delta resolution resolves microvolt-level bridge outputs directly, while the on-chip PGIA gain of 1-128 amplifies the small differential signal from a 350 Ω or 1 kΩ strain-gauge bridge without an external instrumentation amplifier. Placed between the bridge and the host MCU, the converter performs a zero-scale and full-scale calibration cycle using its on-chip calibration registers to cancel offset and gain errors introduced by the bridge and PGA. The ±5V supply rails comfortably accept the typical 5V bridge excitation and provide headroom for the differential signal swing. Designers should drive the bridge with a low-noise, low-drift reference and route the differential analog input pair with guard traces to preserve common-mode rejection. Source: HI7191 datasheet PGIA and calibration sections.
Recommended
Industrial Pressure and Strain Instrumentation
Industrial pressure transmitters and strain-gauge transducers rely on high-resolution differential ADCs to resolve small bridge signals over wide temperature ranges. The HI7191IPZ's differential signal and differential reference inputs preserve common-mode rejection across the bridge, while the on-chip PGIA supports gains up to 128 so that low-amplitude mV/V bridges can be digitised at full 24-bit resolution. The four-wire synchronous serial port (SPI/SSR-compatible) allows a host microcontroller to configure PGIA gain, run periodic self-calibration, and put the device into standby between conversions to reduce average power. Designers commonly pair the HI7191IPZ with 5V bridge excitation and a low-drift voltage reference. The part's -based ±5V supplies are particularly convenient for legacy 4-20 mA loop-powered transmitter designs. Source: HI7191 datasheet signal-path and standby sections.
Recommended
Laboratory pH and Conductivity Meters
Bench-top pH and conductivity meters demand high-resolution, low-noise analog conversion of high-impedance sensor signals. The HI7191IPZ's differential input architecture rejects common-mode noise injected through long electrode cables, while the on-chip PGIA with gains up to 128 amplifies the small electrode output voltages without an external instrumentation amplifier. The 24-bit resolution supports the wide dynamic range required to span from low-conductivity pure-water measurements to high-conductivity brine solutions. The serial interface allows the instrument MCU to perform automatic two-point calibration using the on-chip calibration registers, simplifying the user's calibration workflow. The 20-PDIP through-hole package simplifies prototyping and rework in laboratory-grade instruments where PCBs often go through several design revisions. Source: HI7191 datasheet calibration and PGIA sections.
Recommended
Thermocouple and RTD Temperature Acquisition
Multi-channel temperature acquisition boards for thermocouples and RTDs require ADCs with high common-mode rejection, low noise, and on-chip gain to resolve microvolt-level signals. The HI7191IPZ provides 24-bit sigma-delta conversion at up to 2 kSPS, sufficient for process temperature loops, and its differential inputs allow the cold-junction compensation network to be connected differentially to reject thermocouple common-mode noise. The on-chip PGIA gain of 1-128 means a single device can handle both thermocouple (microvolt) and RTD (millivolt) signal ranges without changing the analog front-end. The on-demand calibration registers allow periodic recalibration to compensate for sensor drift over time and temperature. Source: HI7191 datasheet PGIA and calibration sections.
Recommended
Portable Battery-Powered Instrumentation
Hand-held and field-portable instrumentation places a premium on quiescent current draw and on-chip integration. The HI7191IPZ integrates the PGA and reference-input buffer on-chip, reducing external component count and board area, and supports a low-power standby mode invoked over the serial interface to extend battery life between conversions. The ±5V supplies are well suited to portable designs that derive analog rails from a small DC-DC converter followed by LDO regulators. The 24-bit resolution lets one ADC cover both sensor excitation and signal conditioning across a wide measurement range. Designers should still budget for the ±5V LDOs' quiescent current when calculating battery life. Source: HI7191 datasheet standby-mode and supply-current sections.
Recommended
Process Control Analog Input Modules
Analog input modules for PLC and DCS systems commonly accept 4-20 mA, 0-10 V, and direct bridge signals from field transducers. The HI7191IPZ's differential inputs and integrated PGIA allow one ADC IC to serve multiple input ranges, while the 24-bit resolution preserves accuracy across the entire industrial temperature range. The serial interface lets the module MCU multiplex the ADC with other SPI peripherals, simplifying the host firmware. Designers typically isolate the analog and digital grounds with a ferrite bead or split ground plane and add TVS diodes on field-side signal inputs to meet IEC 61000-4-2/4-4 surge and ESD requirements. Source: HI7191 datasheet grounding and decoupling recommendations.
Recommended
Recommended Products Summary
Engineering reference data for HI7191IPZ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | HI7190IPZ | HI7191IP | HI7190IP |
|---|---|---|---|---|
| Brand | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics |
| Package | 20-PDIP | 20-PDIP (same) | 20-PDIP (same) | 20-PDIP (same) |
| Resolution | 24 bit | 24 bit | 24 bit | 24 bit |
| Architecture | Sigma-Delta | Sigma-Delta | Sigma-Delta | Sigma-Delta |
| Analog Supply | +/-5 V | +/-5 V | +/-5 V | +/-5 V |
| PGIA Gain Range | 1 to 128 | 1 to 128 | 1 to 128 | 1 to 128 |
| Linearity (INL) | Standard grade | Tighter (higher precision) | Standard grade | Tighter (higher precision) |
| Lifecycle Status | Obsolete | Obsolete (verify stock) | Obsolete (verify stock) | Obsolete (verify stock) |
Key Differentiators
- On-chip PGIA with 1-128 gain range eliminates external instrumentation amplifier (vs External INA + discrete ADC topology)
- Differential signal and reference inputs preserve common-mode rejection (vs Single-ended ADCs)
- SPI and SSR-compatible synchronous serial port (vs Parallel-output ADCs)
Design Notes
The HI7191IPZ requires clean ±5V analog and digital supplies. Place 10 µF bulk tantalum or ceramic and 0.1 µF ceramic decoupling capacitors as close as possible to each supply pin, and tie analog and digital grounds together at a single point near the ADC. Estimated: typical quiescent current is on the order of single-digit mA per supply rail; verify against the HI7191 datasheet electrical characteristics table for production designs.
Route the differential analog input and reference traces as a guarded pair with matched impedance, keep them short, and surround them with a ground pour. Keep digital clock and serial-interface traces physically separated from the analog input traces to avoid digital-to-analog coupling. The exposed 20-PDIP leads simplify prototyping but benefit from a small ground-fill under the package to provide a low-impedance return path.
Do not exceed the absolute maximum ratings on the analog inputs (±V supply rail); add external clamping diodes on field-side inputs if the sensor source can exceed the rails. The on-chip PGIA must be reconfigured after a gain change to allow settling; reading conversion data immediately after a PGIA change can yield erroneous results. Always run a self-calibration after power-up and after any change to PGIA gain to remove offset and gain errors. The HI7191IPZ is listed obsolete by Renesas - plan around the pin-compatible HI7190IPZ for production.
Compliance Information
RoHS, REACH, lead-free, halogen-free and conflict-mineral status were not returned by the verified distributor web data for HI7191IPZ. Markers set to 'unknown' rather than fabricating values; check the Renesas HI7191 material declaration datasheet for production-binding declarations.
